Antiskid device



C. C. FARMER ANTISKID DEVICE Filed July 27, 1938 INVENTOR CLYDE C. FARMER I f m ATTORNEY Patented Apr. 23, 1940 PATENT: OFFICE auzrrsxm nnvrcn CLvde 0. Farmer, Pittsburgh, Pa., assignor to- The Westinghouse Air Brake Compa y, Wilmerding, Pa... a corporation of Pennsylvania Application July 27, 1938, Serial No. 221,533

A 11 Claims. This invention relates to antiskid devices for guarding against skidding or sliding of the wheels of vehicles such as railway cars and trains, and has particular relation to a vehicle brake equipment including means-automatically responsive to the slipping of a vehicle wheel due to the application of the brakes for releasing the brakes on the slipping wheel to prevent skidding or sliding thereof. e

In the present application, the term skid" or slide" refers to'thedragging of a vehicle wheel along a road or rail surface in a locked or nonrotative state, whereas the term slip" refers to the rotation of the vehicle wheel at a speed less than that corresponding to vehicle or rail speed at a given instant.

Various devices have been proposed, principally of the rotary inertia type, for effecting release of the brakes on an individual wheel or wheel and axle unit at the instant that the wheel or wheel and axle unit begins to slip, in order to prevent the slipping wheel from decelerating to a locked or non-rotative state and cause it to accelerate back toward a speed corresponding to vehicle or'rail speed. Such devices inherently operate to cause reapplication of the brakes on a slipping wheel before it returns fully to a speed corresponding to vehicle speed.

It is desirable to provide means for preventing reapplication of the brakes on a slippingwheel until after it returns fully to a speed corresponding to a vehicle or rail speed for the reason that the reapplication of thebrakes on a slipping wheel which is accelerating back toward a speed corresponding to vehicle speed may cause it to immediately again decelerate rapidly toward a locked or non-rotative state and, if the speed of the wheel is sufliciently low at the time of reapplication of the brakes, may even cause it to lock and slide.

In addition to insuring against sliding of a vehicle wheel, the holding off of a reapplication of the brakes on a slipping wheel until it returns fullyto a speed corresponding tovehicle or rail speed minimizes the possibility of repeated slipping cycles and thus minimizes the waste of fluid under pressure which would otherwise occur due to the repeated exhausts of fluid under pressure from a brake cylinder. In the case of a single car, repeated slipping cycles and the consequent repeated exhausts of fluid under pressure from the brake cylinder may be tolerable but in the case of a train of cars, wherein a plurality of brake cylinders may be repeatedly exhausted during an application of the brakes, the fluid pressure supply may be reduced to an intolerable degree rendering the application of the brakes on the train inadequate.

It is an object of my invention therefore, provide novel means-for preventing the reappli- 5 cation of the brakes on a slipping wheel until it returns fully to a speed corresponding to vehicle or rail speed.

More specifically, it is an objectwof my inven tion to provide pneumatic timing means which 10 is set in operation upon the slipping of a vehicle wheel .to prevent reapplication of the brakes on a slipping wheel for a certain uniform time regardless of variations in-the rotative condition of l the wheel while slipping. iii

The above-objects, and other objects of 'my invention which will be made. apparent hereinafter, are attained by means of an embodiment of my invention shown in the single flgure of the accompanying drawing. 20

Description of. equipment Referring to the single figure of the accompanying drawing, the equipment shown cornprises one or more brake cylinders H for effecting operation of the brakes associated with a single wheel,- a pair of wheels or a plurality of pairs of vehicle wheels, not shown; a source of fluid under pressure such as a main reservoir I! located upon the control or traction car of a train; a supply pipe l3 connected to the main reservoir and extending throughout all cars of the train; a pipe [4, hereinaften called the straight-air pipe, likewise extending throughout all cars of the train; a manually operable selflapping brake valve l5 for controlling the pressure in the straight-air pipe I; a relay valve device It for controlling the supply of fluid under pressure to and the release of fluid under pressure from the brake cylinder II; a magnet valve device I! for controlling the operation of the relay valve device I 6, a wheel-slip responsive device l8; a pressure-operated switch I 9 responsive to the pressure in the straight-air pipe It; a self-holding electrical relay 20; and a time controlled switch device 2| Considering the parts of the equipment in further detail, the self-lapping brake valve I5 is of the type described and claimed in Patent No. 2,042,112 of Ewing K. Lynn and Rankin J. Bush and it is deemed unnecessary, therefore, to describe the brake valve l5 except functionally. When the operating handle 25 of the brake valve I5 is in its normal brake release position, the brake valve is conditioned to vent the straightair pipe l4 to atmosphere. When the handle is shifted horizontally into a so-called application zone out of its normal release position, the brake valve is conditioned to establish communication through which fluid under pressure is supplied from the supply pipe l3 to the straight air pipe H, the brake valve 15 being automatically self-lapping to establish a pressure in the I straight-air pipe l4 substantially proportionate to the degree of displacement of the operating handle out of its normal release position. Should the pressure in the straight-air pipe l4 tend to reduce, due to leakage or for other reasons made apparent hereinafter, from a pressure corresponding to the position of the operating handle, the brake valve is automaticallyoperative to supply further fluid under pressure to the straightair pipe to maintain a pressure therein corresponding to the position of the handle. The utility' of this pressure maintaining feature of the brake valve I5 will be made apparent hereinafter in connection with a reapplication of the brakes following slipping o'fthe wheels.

The relay valve device, I6 is of conventional type and comprises a suitable casing containing a piston 26 for operating a supply valve 21 of the disc type and a release valve 28 of the slide valve type. The release valve 28 is contained in a chamber 29 at one side of the'piston 26 and is interlocked with the stem 33 of the piston so as to be operatively shifted upon its associated valve seat formed on the casing to lap or uncover an exhaust port'32 opening out of the chamber 29' in correspondence with the movement of the pis-' ton. Chamber 29 is constantly connected to the brake cylinder II, as through a pipe 3|.

The supply valve 21 is contained in a chamber 34 of the casing that is constantly connected to the supply pipe l3 through a branch pipe 35. The supply valve 21 has a fluted stem 36, which operates slidably in a suitable bore 31 in the casing, and a coil spring 38 interposed in concentric relation to the stem 36 between thevalve2l and the .casing yieldingly urges the valve into seated relation on an associated annular rib seat 39 to close communication through a port or passage 4| connecting the chamber 34 and the chamber 29.

The end of 'the piston stem 33 is of reduced diameter and extends through the port 4| into contact with the inner seated face of the supply valve 21.

When fluid under pressure is released from a chamber 42 formed in the casing of the relay valve device l6 at the side of the piston 26 opposite to the chamber 29, the spring 38 yieldingly urges the supply valve 21 into seated relation on the annular rib seat 39 and the valve engages the stem 33 of the piston 26 to shift the piston to a normal position in which the release valve 28 laps or-covers the exhaust port 32. When fluid under pressure is supplied to the chamber 42, the piston is shifted in a direction to unseat the supply valve 21 and at the same time shift the release valve 28 without uncovering the exhaust port 32. Fluid under pressure is thus supplied from the supply pipe I 3 to the brake cylinder II by way of the pipe 35, chamber 34, passage 4|, chamber 29 and pipe 3|. When the pressure established in the chamber 29 is substantially equal to the pressure established in the chamber 42, the spring 38 is effective to reseat the supply valve 21 to cut off the further supply of fluid under pressure to the brake cylinder.

If the pressure in the chamber 42 is reduced The coil spring 46 below the pressure established in the chamber 29 and bralre cylinder H, the piston 26 is shifted in a direction to cause the release valve 28 to uncover the exhaust port 32, the supply valve 21 remaining seated, thus causing fluid under pressure to be released from the brake cylinder.

magnet valve device I! comprises a double beat Va e 45 y urged to an upper seated positron by acoil spring 46 and operated to a lower seated position upon energization of an electromagnet winding or solenoid 41 through the medium of aplunger 48 associated with the electromagnet wrnding. The double beat valve 45 is contained in a chamber 49 in the casing of the magnet valve device that is constantly connected by one section of branch pipe 44 to the chamber 2 0f the e ay valve device l6 and is provided with oppositely extending fluted stems which are 5| thatis constantly open to atmosphere through anexhaust port 5 ,.and the other of which conto a chamber 53, that is constantly connected to the straight-air pipe l4 through the other section of the branch pipe 44. is contained in the chamber 53 and is interposed between the casing and a sc 54 that n ages the end of the fluted stem of the double beat valve within the chamber 53. When the electromagnet winding 41 is deenergized, spring 46 urges the double beat valve 45 to its upper seated position, thus closing communication between the chamber 49- and the atmospheric chamber 5|, and establishing communication between the chamber 49 and the chamber 53 and connecting the chamber 42 of the relay valve dev ce i6 to the straight-air pipe l4. When the electromagnet winding 41 is energized, the double beat valve 45 is. shifted downwardly to its lower seated position to close the supply communication just described and to connect the chamber 49 and atmosphere chamber 5|, thus causing fluid under pressure to be vented from the chamber 42 of the relay valve device IS.-

The wheel-slip responsive device I8 is of the rotary inertia type described and claimed in my coending application, Serial No. 137,956, filed April 20, 1937, now Patent No. 2,140,620 and is illustrative of any suitable type of device for performing a corresponding function.

The wheel-slip responsive device 18 comprises a tubular casing 56 in which is contained a rotary inertia element in the form of a fly-wheel 51, a driving shaft 58 for the fly-wheel, and a switch device 59.

he dr shaft 58 is supported at opposite ends thereof byball bearings 6 I, one of the bearings being contained in the end cover 62 of the casing 56 and the other being slidably supported within a bore 63 in the laterally projecting hub portion 64 of the fly-wheel 51.

The fly-wheel is supported to rotate within the casing by a ball bearing 65, at one end of the hub portion 64, that is arranged to move slidably in a bore 66 of the casing 56 and by another ball bearing 61 at the opposite end of the hub portion in a suitable recess in the face of the fly-wheel, the

ofthe shaft 58 and another pulley fixed to 5 the axleofthe'wheel;

' The-fly wheel 51 is rotated by rotation of the shaft through a clutch arrangement compris- I 1 a-disc 69-fixed,--to;the shaft 58, and a coil 410i. and a collar or fiange "12' fixed to the shaft 58 1 wlthin-ithehub portion 64 of-the fly-wheelas to ifurge theflyjwluee15'!. and'the disc 59 into. interlocklng or clutching engagement. Suitable thrust bearingsfu'fare providedfor'sustaining the axial '13 thrust of thepulley58 on' the end cover 62 due 1 to the-force of the spring I04 and also'the thrust.

of the spring on the fiy-wheel' 51. p

- The disc and fly-wheel 51 are interlocked -br.means of a'plurality of spaced pairs of com- 20 .plementary-registering recesses 15 and 15in the juxtaposed faces of the disc and fiy-WheeL'in each of which-"pairs of complementary recesses is contained a-- steel ball 10. suitable number of pairs of recesses Hand 16 may be provided 26 spaced citcumferentially and radially outward from the.shaft 50. As shown in my copending application "-i'eferred t'dabove', the recesses I5 -.and 18 are relatively short andof uniform curvature aboutflithe axls of the Shanta so that-j '30 therecessesi'resemblesomewhat the contour of a kidney bean. I

Each of the recesses- 15 and I5 varies in depth.

, along theme-thereof, withrespect to the face of the disc or fly-wheelinwhich they are located,

85 beingdeepest at the mid-point and' sloping upwardlylin. opposite directions to the face of the disc or ,fly-wheelr- .It will-thus beseen that under the influence of spring 1|,the steel balls 18 normally seat in the deepest portion of each pairoilcomplementary 45 u is such-asto maintain the fly-wheel s1 and the disc .69 in interlocking engagement, as shown, .as long as the disc does not tend to decelerate or. accelerate with respect-to the fiy-wheel in excess ofga certain rateicorresponding, for example,

50 to a tenmile per hour per second rate of retardation or acceleration of the vehicle wheel driving the shaft 58. Such a high rate of acceleration or deceleration of the vehicle wheels will not occur during an application of the brakes unless by exceeding the limit of adhesion between the vehicle wheel and the rail surface along which the vehicle rolls, that is, by slipping the wheels.

When the shaft 58 decelerates at a rate corresponding to the deceleration of the associated vehicle wheels while slipping, the fiy-wheel 51 tends to over-speed or lead the shaft 50 and when the shaft 58 accelerates according to the rate of acceleration of the vehicle wheel back toward a speed corresponding to vehicle speed while slip- 05 ping, the fly-wheel 5'! tends to under-speed or lag behind the shaft 58.

Due to the steel balls interposed between the disc 09 and the fly-wheel 51, the rotative shift of the fly-wheel 51 either forwardly or back- 70 wardly of its normal position relative to the disc.

' causes the fly-wheel 51 to be shifted axially in the right-hand direction against the yielding resisting force of the spring II.

The degree of rotative shift of the fly-wheel 51 75 relative to disc 69 is limited to prevent the steel balls from leaving the complementary recesses I5 and 18, as by one or more pins not shown, in the disc or, fiy' wheel, that cooperate with arcuate slots org'rooves, not shown,v in' the fly-wheel or:

- disc, such construction beinglpshown in detail ins my above mentioned" copending application;

The w h s e l e l$ }=Wh e 1 p re ponsive; device)"- comprises fa'iapair-gof cooperating resilient contact-fingers llandtlfeachof which is fixed at oneflendjto aniinsulatin'g member]; 10

secured,.w ithin thej .{68 ing reserpine endl'ofi the hub portion-,ofthe flywhee it. The Contact fingers 8| and]! are disposed in'spac ed parallel relation in alignment with; the. axis of the hub portion 64 of the fiy wheei'anda're so spaced that the outer freegends-thereof' are normally dis-J engaged. When the"fiy-wheel 51'isshifted in the right-hand directlonj, as 'aresult of shifting rotativelyrelativeto the disc: 59, the head of a screwplug 84 screwed into the outer open e'nd l0, of the hub-64 of the fiy-wheelengages the free erally against the contact finger 82." A tip'05 of insulating material is provided on the free end of thecontact finger-II- to prevent the direct engagement of the screw plug 84 on the flywheel therewith and the consequent grounding of thecontact finger-BI to'the casing. The pressure switch 19 is 'illustrated in simple diagrammatic form and may comprise a casing containing a piston 91 haviiiga stem $2 on which is carriedin insulated relation a switch mem-' ber 93 "thatjisjadaptedto engage a pair of spaced the piston" SI to a limit position in one direction in which the switch member 031s out of engagement r-with itsassociated contact membersj04. Formed-in the casing on the'side of the piston opposite to the spring 05 is a chamber 96 which is constantly connected to the straightairpipe I4, as through abranch pipe 01.

The spring 9515 of such strength as to maintain the piston ina position that the. switch member 93 is out of engagement with its contact members 94 as long as the pressure in thestraight-air pipedoes not exceed acertain uniform low pressure, such as five pounds persquare inch. When the pressure in the straight-airpipe exceeds the uniform low pressure of five pounds per square inch, the piston 0| is shifted upwardly against the yielding resistance of the spring 05 to effect engagement of the switch member 93 with its associated contact members 04.

The self-holding relay 20 is a conventional type of electrical relay and, as diagrammatically shown, comprises an electromagnet winding IOI effective, when energized, to actuate an associated 6o armature I02 carrying in insulated relation thereon a switch or contact member I03 from a position out of contact with a pair of associated contact members I04 to a position bridging or contacting both said contact members. When the electromagnet winding IN is deenergized, the armature I02 and switch member I03 are biased by a spring, not shown, or by gravity to a position out of ehgagement with the contact members I04. 7

The time-controlled switch 2I, hereinafter referred as the time switch, comprises a pressure switch I05 similar in construction to the pressure switch I9, 9. volume reservoir I06 and a check valve device I01.

The pressure switch I 05 being identical in construction to the pressure switch I9, it is of the bonnet type. The valve I09 is so arranged as to unseat from an associated valve seat formed on the casing to permit the rapid supply of fluid under pressure therepast from a branch pipe III of the brake cylinder pipe 3! to the chamber I08 and thence to the volume reservoir I 06 which is connected to the chamber I08 as through a short pipe connection 2. ',The volume reservoir I06 is also connected to the piston chamber 96 of the pressure switch I05, as by a short pipe I3. l The vvalve I09 of the check valve device I 01 is provided with a restricted port II4 therethrough to restrict the rate of back flow of fluid under pressure from the volume reservoir I06 to the pipe 3|. I

The spring 95 of the pressure-switch I 05 is of such strength that when the fluid pressure established in the volume reservoir I06 and effective in the chamber 96 on the piston '9I of pressure switch I05 exceeds a certain uniform low pressure, such asfive pounds per square inch, the switch member 9a is actuated into contact with its associated contact members 94. Furthermore, the capacity of the volume reservoir I06 is such' with respect to the flow area of the restricted port 4 in the valve we as to delay theoperation of the pressure switch I 05 to a position in which switch member 93 disengages its associated contact member 94 when the pressure in the brake cylinder I I and pipe 3| is reduced below thatin the volume reservoir I 06 'I he electromagnet' winding 41 of the magnet .valve device I! is energized by current supplied ,froma suitable source such as a storage battery I15 which may be the storage battery for the lighting system on the car.

Electrical circuits, which will be specifically described hereinafter in connection with an assumed operation of the equipment, are provided for controlling energization and deenergization of the electromagnet winding 41 of the magnet valve device I 7.

Operation of equipment and then shifting the brake valve handle 25 into the application zone thereof a desired amount.

- The straight-air pipe I4 is accordingly charged to a pressure corresponding to the position of the brake valve handle in the application zone, and, since the electromagnet winding 41 of the magnet valve device I! is deenergized, the piston chamber 42 of the relay valve device I6 is likewise charged through the branch pipe 44 to the pressure established in the straight-air pipe. When the pressure in the straight-air pipe I4 bers 94. Such operation, however, is without eiiect at this time as will be made apparent presently.

The relay valve device I6 is operated in response to the, pressure of fluid supplied to piston chamber 42 thereof. to supply fluid under pressure from the supply pipe I3 to the brake cylinder II, and operates automatically to cut oil? the supply of fluid under pressure to the brake cylinder when the pressure established therein corre sponds to the pressure established in the piston chamber 42.

Fluid under pressure supplied through pipe 9| to the brake cylinder II also flows through the branch pipe III,. unseats the valve I09 and flows at a rapid rate into the volume chamber I06 to cause operation of the switch member 93 of the pressure switch I05 into engagement with its associated contact members 94 when the pressure in the volumechamber is sufliciently built up. Such operation of the pressure switch I05 is, however, without eliect at this time.

If the operator desires to further increase the degree of the application of the brakes, he may do so by further shifting the brake valve handle operated to vent fluid under pressure from the brake cylinder until the pressure in the brake cylinder corresponds to the reduced pressure in the straight-air pipe [4.

, If the operator desires to completely release the brakes, he merely returns the brake valve handle 25' to its normal release position to reduce the pressure in the straight-air pipe I4 to atmospheric pressure, thus causing the relay valve device I6 to operate to completely vent fluid under pressure from the brake cylinder I I and thus completely release the brakes.

In the above operation it was assumed that none of the wheels on the car or train slipped.

It will thus be observed that as long as none of the wheels on the car or train slip, the operation of the brake equipment is similar to that of conventional fluid pressure brake equipment.

Let it now be assumed that upon an application of the brakes, a wheel with which the brake cylinder I I is associated begins to slip. Practically instantaneously with the initiation of slipping oi the wheel, the wheel-slip responsive device I8 operates to effect engagement of the contact fingers 8| and 82 of the switch device 59 thereof. The closing of the switch device 59 completes a circuit for energizing electromagnet winding 41 of the magnet valve device I1, this circuit extending from one terminal, hereafter considered as the positive terminal, of the battery] I5 through 93 of the pressure switch I9,-'and a wire I24 which is connected to the negative terminal of the batteryIIS.

The electromagnet' winding of the relay 20 is connected in parallel relation to the electromagnet winding 41 of the magnet valve device I1, and is thus energized simultaneously with the energization of the electromagnet winding 41, to shift the switch member I03 into contact with its associated contactmembers I04. A holding circuit is accordingly established for maintaining the electromagnet windings 41 and |0I energized independently of the switch device 59 of the wheel-slip responsive device I8, such circuit extending from the positive terminal of the battery II5 through wire II1, contact members I04 and swit'chmember I03 of the relay 20, a wire I26, contact members 94 and switch member 93 of the pressure switch I05, wire H9, in parallel through electromagnet winding 41 of'the magnet valve (16-.

vice I 1 and electromagnet winding |0| of relay 20, wire I23, contact members 94 and switch member 93 ofthe pressure switch I9, and wire I24 to the negative terminal of the battery 'I I5. Relay 20 is accordingly termed a self-holding relay because it'establishes its own holding circuit.

Upon the energization of the magnet winding 41 of the magnet valve. device I1, fluid under pressure is rapidly vented from the piston cham ber '42 of'the' relay valve device I6 through the exhaust port 52 oi the magnet valve device I1,

' ,and thejrelay' valve device I6 is correspondingly operated'to rapidly vent fluid under pressure from the brake cylinder through the exhaust port 32. At the same time, fluid under pressure in the volume reservoir I06 escapes therefrom at a relatively'slow-rate through the restricted port 4 in thevalve I09 of the check valve device I01 into brake cylinder pipe 3| and exhausts to atmosphere through-the exhaust port 32 of therelay valve device I6. v i

The rapid reduction of the pressure in the brake cylinder II and the consequent rapid reduction in the degree of application of the brakes is effective to cause the slipping wheel to cease deceleration and begin to accelerate back toward a speed corresponding to vehicle or rail speed before actually reaching a locked or sliding condition.- When theslipping wheel changes from deceleration to acceleration, the switch device 59 of the wheel-slip responsive device I8 is momentarily opened due to the fly-wheel 51 shifting from a leading position to a lagging position through its normal position in response to'the change in the rotative condition of the slipping wheel.

Since the magnet winding 41 of the magnet valve device I1 is maintained energized by the holding circuit including the relay 20 and the pressure switch I05 of the time switch 2|, the

momentary opening of the switch 59 of the wheelslip responsive device I8 is without effect and the relay valve device I6 remains conditioned to continue to vent fluid under pressure from the brake cylinder I.

When the slipping wheel approaches closely to a speed corresponding to vehicle speed and the rate of acceleration thereof decreases sufliciently,

the switch 59 of the wheel-slip responsive device IB is again opened due to the return of the fly-wheel. 51 to-its normal position with respect to disc 69.- In such case also, the opening of theswitch .device'59 is without efiect since the magnet winding 41 of the magnet valve device I1 continues to remainenergized' over the holding area of the restricted port 4 in the valve I09. of the check valve device I01 that the pressurein the volume reservoir I06 effective to maintain the switch member 93 of the pressure switch I05 in contact with its associated contact members 94 does not reduce sufliciently to cause separation of theswitch member 93 from its associated contact members 94 until the slipping wheel has definitely and fully returned to a speed corresponding ,to vehicle or rail speed. Obviously the volume of the reservoir I06 and the size of the restricted port I I4 of the valve I09 may be varied so as to effect any desired time delay interval over which the pressure switch I05 is maintained in circuit-closing position following the initiation of venting of fluid under pressure from the brake cylinder II. p a

When the pressure in the volume reservoir I06 has reduced sufficiently, the switch member 93 of the pressure switch |05jis shifted out of engagement with the contact members 94 and the holding circuit, previously described, for maintaining the magnet winding 41 of the magnet valve device I1 and magnet winding |0| of relay 20 energized is interrupted.

The magnet winding 41 of the magnet valve device I1 is accordingly deenergized and the double beat valve 45 of the magnet valve is returned to its upper seated position reestablishing the supply communication from the straightair pipe I4 to the piston chamber 42 of the relay valve device I6. The relay valve device I6 is accordingly again operated to supply fluid under pressure from the supply pipe I3 to the brake cylinder thereby effecting reapplication of the brakes on the wheel or wheels which slipped.

The supply of fluid under pressure to piston chamber 42 of relay valve device I6 tends to reduce the pressure in the straight-air pipe I4 but brake valve I5 operates automatically to supply fluid under pressure into the straight-air pipe I4, as previously pointed out, so that a pressure is maintained in the straight-air pipe corresponding to the displacement of the brake valve handle 25 out of its release position into the application zone.

Since it is customary for the engineman of a railway train to reduce the degree of a brake application as the speed of the train reduces, for well understood reasons, the operator of the present equipment may have returned the brake valve handle toward its release position from the position in which the slipping of the wheels was initiated. Thus, the pressure reestablished in the brake cylinder may be less than that which initiated the slipping of the wheels so that recurrence of wheel slipping is unlikely.

In the event that the vehicle wheel should again begin to slip due to the reapplicationoi the brakes thereon, the equipment again operates in the manner just described to release the brakes and restorethe vehicle wheel to a. speed corresponding to vehicle or rail speed before again reapplying the brakes.

It will beseen that whether a vehicle wheel slips one or more times during. a brake application, the reapplication of the brakes is not ei fected in any event before the vehicle wheel returns fully to a speed corresponding to vehicle or rail speed. Furthermore, since the time switch 2| causes continued reduction of pressure in the brake cylinder ll over the entireslippln Pe l- Hod, "adequate reduction in the vpr1':ssure of jthe brakeicylinder isassured even incases where the ke shoes may stickto the tread "or. rim: or e vehicle wheels and thus notin'stant upon a redu he i 'z to interrupt theflholding circuit r the tva'.1vedevice I I; it will the apparent that tire is always; restored in the brake cylinder he hejcaror train comes to 'a complete enabling all brake cylinders on, the

p j emram to be eiifective tohold ,thecar l or t trainonagrade;

,When it is'desiredto release thebrakesj rior the car, the operator merely M posion of the pressurein the straight-air" pipe I to atmospheric pij 7 ;the pressure switch I! is or course operated to circuit-opening position 1 and thus assuresjthe interruptionjjof all theelec trical brake control circuits while jtheibrakes are ,a" vehicle andthe' wheel races uef qthe a ply cation or excessive propulsion torque to, the.

fiwheel theclosing ottheswitch device 59 in re-' 1 to-such' racing is inetfectiveto c'auseenergization or the magnet is valve 11,; With the straight-air pipe ll ivented to atnios hereisuch exiergizationv o! the magnet valve device i1 would ,not result in any objectionable operation. Hawever, thepressure switch I! preventss'uch ener- Y gization and accordingly the unnecessary con sumption of current from the bat HI; I

t will faccordi operate automatically when a vehicle wheel bengly be seen thatI have v ginsgto'slip torapidly,vent jfluidjunder pressure n from; the brake cylinder 'efiecting applicationfoi the brakes on theislippingjwheehto cause the vehicle wheel'tofcease deceleration and accelerate Iback toward a speed corresponding vehicleior I rail speed withoutY-actuallv,reachingfa locked state and sliding. twill bes'eenalsothataccording ;to' my invention the brake equipment d includes pneumatic time x which 'I have disclose 1 1 me hm a or adeq a r ti the j brake cylindenpresjsure as well as the prevention of the reapplication of the brakes prior to -.the..time. thatthe vehicle wheels'fullyf and definitely return to a speed corresponding v k equipment and described'mayfbe duplicated in part onallcars or cartrucks'oiat'rain so asto guard againstslidingof' a me car wheels onxa train. whilej I n'hav'e described onlyone specific embodiment 0t invention it should be appar- Hentith'atvarious omissions, additions or modifications may {be mjii em the embodiment ishown ,without departing fromfthespirit'of mjyl nventhe scope offmy invention except asit is neces- "s tated by the "scope o'fthe prior art.

Having ow described my inventiom what I jclaim as and desire to secure y Letters Patentfis: U Q i In avehice wheel i l l H m n al 'vice avi a Q munieation'throug isreleased to I 2; Inafvehicle'wheel brake equipment the; t 'bination Lot a magnet ValveQdeiv'iQe ;norni'all y" de energized and effective when deenergized to tablish a' commun icati n through which nu: underpressure m y through which fluid; under) pressure is to: eife'ct release of the brakes, meansfoperative; when the vehlclewheel slips'dueto application 1 of the brakes thereon for eii'ecting energization ofsaidmagnet valved'evice," and means: rendered! effective at the instant the wheel begins to slip for i maintaining said magnet valve device n5 gized for a certain limitedjtime the following the initiation or slipping of the w in a position to establish" a communication through which fluid" under ressure my be supplied to en'ectapplication of the brakeson'a-ve-V hicle wheel andoperative' upon a change, ,inkthe; degree, of energization thereof p gamnerenap i g sition in which it closes said communication and 1 "brake equipment adapted" to ferent position for a certainlimited time fol-Q lowing the initiation or slipping oithe wheels 4. In a vehicle wheel brake equipment, the combination of a magnet valve device normally in a position to establish a "communication-j through which uid under pressure maybesup plied: to eii'ect an"appl icationtfof the" brakes.

a vehicle wheel and'operative to 'afliii'eifent po sition in whichsaid' communicat i i a different communication is establishedthrfougl'i which-1 fluid under' pressure is released toefl'ect by eflectenergizationof said rnagnetvalve device and the operation thereotutofitssaid diii'erent an electroeresponisive switch deviceo'perative to a position to: close said second circuitwhenfthe n wheel begins to sliptomaintainsaid magnetfva-lve brake equipment, =thedevice energizeddndependentlyof. said xflrstgcir-y a time-controlled'iswitch'= devicefor in-l establishes a diflerent 'communicationmthrough which fluid under pressureisreleasedto; eilect release ofthe brakes, means operative when th vehicle wheel slips due? to application otgfthe j brakes thereonifor eflecting ayariation ot the terrupting saidsecond circuita' certain limited time after said valve device operates tov initiate the release of the brakes.

. 5. In a vehicle brake equipment, the combination of a magnet valve device normally deenergized and efiectivewhen deenergized to estabreleased to effect release of the brakes, means operative when the vehicle wheel begins to slip for efiecting energization of said magnet valve device, switch means for establishing and maintaining a holding circuit for maintaining said magnet valve device energized inresponse to the initial energization of the magnet valve device,

and a. time-controlled switch means for inter-- rupting the holding circuit of the magnet valve device to cause. return of the magnet valve device to its normal position only when a certain ulimited time has elapsed after the magnet valve device is initially energized.

6 In avehicle brake equipment of the type having a brake cylinder to which fluid under pressure is supplied to effect application of the brakes on a vehicle wheel and from which fluid under pressure is released to efiect release of the brakes, the combination of a relay valve device operative in response to the pressure of fluid sup-' plied thereto to establish a corresponding pressure in the brake cylinder, valve means normally in a position to establish communication through which fluid under pressure may be supplied to the relay valve means and operative to a different position to interrupt said communication and establish a difierent communication through which fluid under pressure is released from the relay valve means to effect release of fluid under pressure from the brake cylinder, means operative when a vehicle wheel begins to slip for effecting operation of the valve means to its said different position, means providing a,chamber arranged to be charged with fluid under presure when fluid under pressure is supplied to the brake cylinder and from which fluid under pressure is released when fluid under pressure is released from the brake cylinder, means for restricting the reduction of pressure in the said chamber to a rate slower than that of the brake cylinder, and means controlled-by the pressure in said chamber for maintaining said valve means in itssaid different position as long as the pressure in said chamber exceeds a certain uniform pressure. a

' '7. In a vehicle brake equipment, thecombination of a magnet valve device normally deenergized and effective when deenergized to establish communication through which fluid under pressure may be supplied to effect an application of the brakes on a vehicle wheel and effective when energized to close said communication and establish a different communication through which fluid under pressure is released to effectrelease of the brakes, a first circuit including said magnet valve device, means operative when the vehicle wheel begins to slip for closing said first circuit to effectenergization of said magnet valve device, a second circuit including said magnet valve device, an electroresponsive means in parallel relation to said magnet valve device and operative upon energization to complete said second circuit to maintain said magnet valve device and itself energized independently of the first circuit, and time-controlled switch means for interrupting said second circuita certain limited time after said first circuit is initially energized.

8. In a vehicle brake equipment of the type having a brake cylinder to which fluid under pressure is supplied to effect an application of the brakes on a vehicle wheel' and from which fluid under pressure is released to effect release of the brakes, the combination of a relay valve device operativein response to the pressure'of fluid supplied thereto to establish a corresponding fluid pressure in the brake cylinder and in response to the reduction of pressure supplied thereto to efiect a corresponding reduction of the pressure in the brake cylinder, valve means normally in a position to establish communication through which fluid under pressure may be supplied to the relay valve means and operative to a different position to close said supply communication and establish a different communication through which fluid under pressure is released from the relay valve means, means effective when the vehicle wheel begins to slip to effect operation of the said valve means to its said different position, means providing a chamber, a check valve device adapted to permit the rapid supply of fluid under pressure therepast from the brake cylinder to said chamber and to permit only a restricted back flow of fluid under pressure therepast from the said chamber, and means effective as long as the pressure in said chamber exceeds a, certain uniform pressure following the initiation of the slipping of the wheel for preventing the return of said valve means from its said difierent position to its said normal position.

9. In a vehicle brake equipment, the combination of a magnet valve device normally deenergized and effective when deenergized to establish a communication through which fluid under pressure may be supplied to effect an application of the brakes on a vehicle wheel and effective when energized to close said communication and establish a different communication through which fluid under pressure is released to effect release of the brakes, inertia operated switch means efiective to cause energization of said magnet valve device as long as the vehicle wheel is decelerating or accelerating in excess of a certain rate while slipping due to application of the brakes, electroresponsive switch means adapted to be energized and deenergized together with the said magnet valve device, a pressure operated switch device operative in response to the pressure of fluid supplied to effect application of the brakes to a position where conjointly with said electroresponsive switch device it is effective to maintain said magnet valve device energized notwithstanding the operation of the inertia operated switch device to a position for effecting deenergization of the magnet valve device, and means for reducing the pressure actuating the pressure switch at a restricted rate when the release of the brakes is initiated in response to slipping of the vehicle wheel whereby to maintain said pressure switch in a position to maintain the magnet valve energized for a limited time following the initial energization thereof by the inertia operated switch device.

10. In a vehicle brake equipment, the combination of a brake cylinder for operating the brakes associated with a vehicle wheel, relay valve means operatively responsive to variations of a vary the ntrol fluid pressure ftoicorrespondingly Y i i use, of;; the brakespmeani: eflectlve in p'ping' ot'thewheei during: an applicetion'of,

brakes for] effecting such v nauonogthe ntrol pressureastoicause the relaivjvalve means Vary the. pressure in we brakefcylinderso eflect' release; of theibrakes; ind means eilec e; fonce ther'elavivalve means is operated und control of thee last said means'c tdvuryljthe "p assure inthe -braiie-cylinder 1 so as to release brekes to' cause the'relay valve-means to time to so vary the pressure'iny the r ke iiectzthe continued reducti in i a brake "cylinder for" operating" the associated witha" vehicle wheel, relay valve "an-increuseoi a rrespondlng pressure to the brake cylinder-to e ct application of--the.brakes and responsive toi'a reductionor thecontroirpressure for re- 08,082 i i cylinder to elect r elease oi thebrakesineany providing a communication through which the: control: fluid pressure is supplied to fand released iron the relay valve mean s frngnuelly controlled 1 means for controlling the "supply: of fluidunden pressure-to andthe release or fluid under press r a val e n; w fi said #e'i! r1 d" t eans gndi the nignuellyfcon trolled means in said communication eflectiv in ne5positi n-1toopen said com 'operat'iveto asecon'd position to! efluidkpressure in the brake cylinder to elect ations of the deg'ree of application and the dependently of subsequent ing fluid under fpressure from the hreke sure i'rom' the communication, the relay valve niunicdtion and; at the leu se'oi the control fluid pressure Irornfthe reliiy j valve meuns 'so asto efiect to its said second position" valveflnieans thereafter in tion for a. certain'limited' tive condition of the wheel.

i-eleu'sioffthe brakes; 1p);

=inde'pendently of "theinianueliy 'centrolled inegns,

s means'to] its said second position; and mean reflective-once the said valve me insisoperuted firiainta'inin the its sdidsecond posi-P thereafter in-I1 es inthe rotnfor time cheng cnmm c.

ind gnatio and efefrect mere 

